Performance comparison of two implementations of TCM for QAM

Abstract

Trellis-Coded Modulation (TCM) is employed with quadrature amplitude modulation (QAM) to provide error correction coding with no expense in bandwidth. There are two common implementations of TCM, namely pragmatic TCM and Ungerboeck TCM. Both schemes employ Viterbi algorithms for decoding but have different code construction. This thesis investigates and compares the performance of pragmatic TCM and Ungerboeck TCM by implementing the Viterbi decoding algorithm for both schemes with 16-QAM and 64-QAM. Both pragmatic and Ungerboeck TCM with six memory elements are considered. Simulations were carried out for both pragmatic and Ungerboeck TCM to evaluate their respective performance. The simulations were done using Matlab software, and an additive white Gaussian noise channel was assumed. The objective was to ascertain that pragmatic TCM, with its reduced-complexity decoding, is more suitable to adaptive modulation than Ungerboeck TCM.